Low-loss reverse blocking IGBT with PNM structure and trench collectors

A reverse blocking insulated gate bipolar transistor (IGBT) with partially narrow mesa (PNM) structure and trench collectors is proposed. An n-type carrier stored (n-cs) layer is introduced between two trench gates with the bulgy bottom, forming the PNM structure, which nicely shields high electric field from the n-cs layer at the forward blocking state. Hence, a highly doped n-cs layer can be used to enhance the carrier storage effect in the n-drift region at on-state to reduce the on-state voltage [V CE(sat)]. Besides, an n-buffer layer is introduced between two trench collectors at the back side, acting as a field-stop (FS) layer at forwarding blocking state. At the reverse blocking state, the trench collectors shield high electric field from the n-buffer region and the n-cs layer acts as an FS layer, which ensures a high reverse breakdown voltage. Numerical simulation results show that the 1.4 kV proposed reverse blocking-IGBT can use a 38% thinner n-drift region and obtain a 45% lower V CE(sat) than the conventional counterpart.